The invention relates to an X-ray image taking apparatus, more specifically, a mechanism for attaching a plane type radiation detector unit to a C-arm type diagnostic apparatus or fluoroscopic radiographing stand, and input/output (hereinafter referred to as xe2x80x9cI/Oxe2x80x9d) cables of a signal and a power source thereof.
With a spread of a digital radiographing (hereinafter referred to as xe2x80x9cDRxe2x80x9d) apparatus, its clinical use has been extended on various fields from an alimentary canal examination to an interventional radiology (hereinafter referred to as xe2x80x9cIVRxe2x80x9d) for a non-blood vessel system and a simple digital subtraction angiography (hereinafter referred to as xe2x80x9cDSAxe2x80x9d).
In addition to the general fluoroscopic radiographing stand, there is an IVR-digital correspondence type fluoroscopic radiographing stand equipped with a C-arm, wherein a digital image processing device is made small in size and high in performance; an operation ability with an X-ray high voltage device is improved; an image intensifier (hereinafter referred to as xe2x80x9cI.I.xe2x80x9d) has a high image quality and a lower distortion; and transfer and preservation of a full digital image are contrived by employing a 4 million pixel CCD camera of a high density resolving power.
FIG. 3 shows a C-arm type X-ray image taking apparatus wherein a TV camera 19 using CCD and an I.I. 18 are provided on a C-arm 14 rotated around a body axis of an object or patient 9 to face an X-ray tube 12 sandwiching therebetween a top board 10, on which the object 9 to be tested is received. In order to provide fluoroscopy or radiograph with X-rays from various angles with respect to the whole body of the object 9, the I.I. 18 and the X-ray tube 12 are rotated in the C directions around the body axis of the object 9 by the C-arm 14, and moved parallel in the A directions, i.e. head-feet directions of the object 9 along a height direction moving guide 15. The I.I. 18 is moved in the D directions on the supporting plate 17 so that the I.I. 18 can be moved to and from the object 9. Also, the I.I. 18 and the X-ray tube 12 can be rotated around the supporting point of the C-arm 14 in the directions of the head-feet of the object 9. The top board 10 can be rotated in the B directions by a rising-falling C-arm 13. As described above, the fluoroscopic radiographing positions can be taken with various angles without moving the object 9.
In the X-ray image taking apparatus using the I.I. 18, since the I.I. 18 is large, when an operator operates the apparatus in the vicinity of the object 9 and when the evacuation is required, the I.I. 18 is moved in a vertical direction.
Recently, in place of the I.I. 18, a plane type radiation detector has been applied to the X-ray image taking device. The plane type radiation detector is normally formed of an X-ray converting film for converting X-rays into light, photo diode arrays arranged in a matrix shape right under the X-ray converting film; and TFT switches connected to the respective photo diode arrays. The plane type radiation detector has two types. In one type, after X-rays are irradiated, the respective TFT switches are sequentially turned on, so that signal charges accumulated in the respective pixels are read out to form an X-ray image. In the other type, there are provided radiation sensor arrays formed of a converting layer for directly outputting charge signals sensitive to radiation and corresponding to incident amount, and the TFT switches are connected to electrodes arranged in a matrix shape right under the radiation sensor arrays. In use, the respective TFT switches are sequentially turned on, so that signal charges accumulated in the respective pixels are read to form an X-ray image. The latter is explained in the following.
FIG. 4 shows a detector cassette 21, wherein a plane type detecting portion 22, power source 26, control circuit portion 25, gate circuit portion 23, reading circuit portion 24 and image memory 27 are built in, and a connecting terminal 28 for external connection is provided. The gate circuit portion 23 and the reading circuit portion 24 are controlled from an outside at the control circuit portion 25 through the connecting terminal 28, and charge signals accumulated in the condensers of the pixels formed of semiconductors in the detecting portion 22 are read in the reading circuit portion 24 and stored in the image memory 27. Then, the data is transferred outside through the connecting terminal 28. The detector cassette 21 is attached to a detecting portion attaching frame of the X-ray image taking apparatus, and a signal cable is connected to the connecting terminal 28.
FIG. 5 shows a detector cassette 21, wherein a plane type detecting portion 22, power source 26, control circuit portion 25, gate circuit portion 23, reading circuit portion 24, image memory 27 and a communication circuit 29 are built in, and input/output of signals with an outer portion are carried out by a communication circuit through radio signals. The gate circuit portion 23 and reading circuit portion 24 are controlled from the control circuit portion 25 through the communication circuit 29 by radio signals from the outside, and charge signals accumulated in the condensers of the pixels formed of the semiconductors at the detecting portion 22 are read in the reading circuit portion 24 and stored in the image memory 27. Then, if necessary, the data is transferred outside from the communication circuit 29. The detector cassette 21 is simply attached to the detecting portion attaching frame of the X-ray image taking apparatus, and output and input of the signals are carried out by radio signals through the communication circuit 29, so that a connecting cable is not required.
FIG. 6 is a sectional view showing a structure of a pixel 30 for constituting the detecting portion 22 of the plane type radiation detector. The pixel 30 includes an active matrix board, wherein electrode wirings, such as gate line and reading signal line, a thin film transistor TFT 32 and a condenser 38 are formed in an X-Y matrix shape on a glass base board; an X-ray converting layer 37 extending over the substantially whole surface above the active matrix board; a pixel electrode 31 positioned thereunder; and an upper electrode 36 located thereabove.
The X-ray converting layer 37 has good photoconducting characteristics according to the irradiation intensity of X-rays to generate a charge signal. For example, a film having a large area can be formed easily by vapor deposition, and amorphous selenium (hereinafter referred to as xe2x80x9ca-Sexe2x80x9d) or the like formed in a film having a thickness of 300 to 1,200 xcexcm can be used. The upper electrode 36 of the X-ray converting layer 37 is formed on a surface at the X-ray incident side, and the pixel electrode 31 is formed at a position corresponding to each pixel 30 on a side opposite to the X-ray incident side.
The condenser 38 is connected between the pixel electrode 31 and the ground. Also, a bias voltage is applied to the X-ray converting layer 37 from a bias applying portion, and a charge generated at the X-ray converting layer 37 according to an X-ray irradiation intensity is accumulated in the condenser 38.
The TFT 32 has a signal reading switch function and is arranged in two dimensions every pixel 30. And, the charge signal of the condenser 38 is read out by a switch pulse from a gate line terminal 33a to the reading circuit portion 24 through a reading signal line terminal 34a. 
FIG. 7 shows a circuit diagram for explaining operations of the plane type radiation detector. The respective pixels 30 are regularly arranged in the length and width directions on the active matrix board 35. The gate circuit portion 23 is driven by the signal from the control circuit portion 25, and pulse signals G1, G2, G3, . . . are sequentially sent to the gate electrodes of the TFTs 32 connected to the pixel electrodes 31 of the respective pixels 30 from the row direction through the gate lines 33. On the other hand, the reading circuit portion 24 is driven by a signal from the control circuit portion 25, and image charge signals of the respective pixels 30, i.e. R1, R2, R3, . . . are sequentially read from the drain electrodes of the TFTs 32 from the column direction through the reading signal lines 34.
In the conventional plane type radiation detector and X-ray image taking apparatus structured as described above, in case the detector cassette 21 as shown in FIGS. 4 and 5 is attached to the C-arm type X-ray image taking apparatus or the general fluoroscopic radiographing stand, there is a problem such that a large attaching mechanism is required for fastening the detector cassette 21.
Also, a cable for inputting or outputting a signal into or from the detector cassette 21 has to be connected. In the power source built-in type detector cassette 21, since a large battery is required, the cassette 21 becomes heavy, so that the battery having a sufficient power source capacity can not be mounted.
Also, when an examination starts or terminates, in case the object or patient 9 gets on or off the top board 10, a detector system, i.e. detector unit, or I.I. 18 and TV camera 19, physically stands on the way of getting on or off the top board 10 of the object 9. Therefore, it is required to move the C-arm to a position where the C-arm does not bother the object 9 in getting on or off the top board 10, or to move the detector system along the supporting plate 17 located at an end portion of the C-arm 14. Thus, time and labor for moving the detector system are increased.
Also, recently, through the introduction of an ultrasonic wave diagnostic apparatus into an examination room, while observing a fluoroscopic image on an X-ray TV monitor and an ultrasonic wave image on a monitor of the ultrasonic wave diagnostic apparatus, there have been increased an examination and treatment by inserting a needle or the like into the object or patient 9. In case a prob of the ultrasonic wave diagnostic apparatus is operated, the operator inevitably stands near the detector system, i.e. detector unit or I.I. 18 and TV camera 19. In case the fluoroscopy is not carried out, the detector system, i.e. detector unit or I.I. 18 and TV camera 19, interferes with the operation, so that the C-arm has to be evacuated whenever it is not used or returned to the proper position whenever it is used.
In view of the above problems, the present invention has been made, and an object of the invention is to provide a plane type radiation detector unit and an X-ray image taking apparatus, which can be used effectively. Namely, in case the plane type radiation detector is attached to a fluoroscopic radiographing stand of a C-arm type X-ray image taking apparatus or the like, a large attaching frame is not required; when a signal is sent out to or received from the outside, a connector and a cable are not required; it is not required to mount a heavy battery to a detector cassette; in case the object or patient 9 gets on or off the top board 10 when a test starts or terminates, the detector system is located away from the object 9; and further, when the operator carries out the inserting examination or treatment with a prob by using an ultrasonic wave diagnostic apparatus together with the X-ray image taking apparatus, the detector system can be easily evacuated.
Further objects and advantages of the invention will be apparent from the following description of the invention.
In order to attain the above objects, according to a first aspect of the invention, a plane type radiation detector unit is formed of an X-ray converting layer sensitive to X-rays and outputting a charge signal corresponding to an intensity of incident X-rays; an active matrix board having switching elements arranged in a matrix shape and connected right under the X-ray converting layer; a gate circuit portion for sequentially turning on the respective switching elements through gate lines when the signals are read out; a reading circuit portion for reading charge signals accumulated in the respective pixels through reading signal lines; and a control circuit portion for controlling the gate circuit portion and reading circuit portion. The radiation detector unit includes a rotating shaft provided on one end side thereof.
According to a second aspect of the invention, an X-ray image taking apparatus is equipped with the plane type radiation detector unit having a plurality of slide electrodes disposed on the rotating shaft, and a plurality of slip electrodes contacting the slide electrodes provided to the rotating shaft which supports the plane type radiation detector unit.
According to a third aspect of the invention, the X-ray image taking apparatus equipped with the plane type radiation detector unit includes, in an inner portion of the plane type radiation detector unit, a communication circuit portion for receiving radio control signals from an outside to control the control circuit portion and for sending radio output signals from the reading circuit portion; and a remote control reading portion for receiving radio input signals from or sending radio output signal to the outside through the communication circuit portion.
In the plane type radiation detector unit and the X-ray image taking apparatus structured as described above, the rotating shaft is provided to one end side of the plane type radiation detector unit, and the plural slide electrodes are disposed on the rotating shaft. Also, the plural slip electrodes contacting the slide electrodes are located on a side of the X-ray image taking apparatus for supporting the rotating shaft, and, if necessary, the communicating circuit portion is disposed in the plane type radiation detector unit to receive the radio input signals from or send the radio output signals to the outside.
Since the plane type radiation detector unit is held by the rotating shaft, a large attaching frame is not required. Also, since the input or output of signals from or to the outside is continued by the slide electrode and the slip electrode, connection through a connector and a cable is not required. Also, since a power source can be taken from the slide electrodes, it is not required to mount the heavy battery to the detector cassette. Further, in case the test starts or terminates, when the object to be tested gets on or off the top board of an inspection table, or when an operator operates a probe by using an ultrasonic wave diagnostic apparatus together with the X-ray image taking apparatus to carry out the inserting examination and medical treatment, the detector system can be easily evacuated by rotating the rotating shaft by 90xc2x0. Also, if necessary, input or output signals can be received or sent through radio communications between the outside remote control reading portion and the inner communication circuit portion.